a. Field of the Invention
The present invention pertains generally to machines that dispense sealant material to closures and specifically to the dispensation of sealer material to non-circular and circular can or bottle closures.
b. Description of the Background
Sealant is often applied to closures such as can lids and bottle lids prior to joining the closures to the container body. The sealant, also known as “compound” within the industry, may be dispensed in liquid form on the closure. The dispensing technology is well developed for circular can closures.
Non-circular cans, such as rectangular, square, oval, or ham-shaped, pose a significant difficulty for application of the sealant. The need to precisely control the amount of sealant while processing the closure at a high rate of speed poses a high degree of difficulty for the machine designer. Maintenance of high-speed machines further dictates that machines must be designed to be as simple and easy to repair as possible.
The sealant should be dispensed in a controlled manner to limit any excess sealant material on the closure. Excess sealant, while not dangerous if in contact with foodstuffs, adds additional costs to the can and may be squeezed out of the intended location during the process of seaming the closure to the can. Given the large number of closures that may be processed, saving a small amount of sealant on each can closure can translate into substantial cost savings. The prior art includes machines for placing sealant onto circular closures. These machines generally have a sealant dispenser that dispenses the sealant material onto a spinning closure. The closures are presented to the sealant dispenser on a chuck that lifts the closure into place and rotates the closure underneath the sealant dispenser. Machines for dispensing sealant material onto circular closures are capable of running at very high speeds.
However, methods for placing sealant onto non-circular closures have been only marginally successful. One method is similar to pad printing wherein an applicator places the sealant material onto a non-circular can closure by pressing a sealant-dipped applicator onto the closure periphery surface. Such printing-type methods use a large amount of sealant and are not very accurate. These techniques are only used for small batch runs.
An additional method for placing sealant onto non-circular closures is to position the closure under a showerhead and flood the periphery of the closure with sealant. This method also uses large amounts of sealant, and is not very accurate. Additionally, the showerheads require constant cleaning and blocked holes can cause a gap in the sealant.
In another machine, a sealant dispenser is moved in and out along a radius with respect to the rotating axis of the closure. Such machines are a simple modification to the existing circular closure-processing machine. However, the mass of the sealant dispenser limits the speed at which the machine may operate. Such a system is shown in U.S. Pat. No. 6,391,387 issued to Rutledge, et al. on May 21, 2002 which is specifically incorporated herein by reference for all that it discloses and teaches.
It would therefore be advantageous to provide a high speed, highly accurate method and apparatus for dispensing sealant to irregularly shaped closures.